Fire bomb fuze



FIRE BOMB FUZE Oliver J. Vogel, Jr., Bel Air, and Robert B. Wheeler, Aberdeen, Md., assignors to the United States of America as represented by the Secretary of the Army Filed Feb. 6, 1959, Ser. No. 791,781

1 Claim. (Cl. 102--76) (Granted under Title 35, US. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment to us of any royalty thereon.

This invention relates to fire bombs of the type which are carried on the lower side of the wings of airplanes. Specifically, it relates on an improved arming system for the fuzes of such bombs which overcomes certain disadvantages associated with the system now in use.

In the drawings:

Figure 1 is a side elevation, diagrammatic in character, showing a bomb involving our invention and its relation to the airplane.

Figure 2 is a longitudinal section of the fuze constituting part of our invention.

Figure 3 is an end view of the yoke 41 of the fuze of Figure 2.

Figure 4 is a longitudinal section of the yoke on the line 4-4 of Figure 3.

Wing-tip fire bombs, usually filled with gelled gasoline, are important military weapons. They are carried beneath the wings of airplanes in the same manner as auxiliary fuel tanks. They are provided with impactsensitive fuzes which should become armed only after the bomb has left the airplane.

These fuzes are ordinarily essentially of the type shown in Patent No. 2,420,662, granted May 20, 1947 to Frank B. Hale. The safety wire 18 of the Hale patent is fastened to the wing of the airplane, so that it is withdrawn when the bomb is dropped. To provide for a delay the safety pin 13 is threaded into the head 14 and provided with anemometer blades which rotate the pin and thus cause it to be withdrawn after the bomb has fallen a certain distance. To prevent rotation of the pin by the anemometer blades while the bomb is on the plane, the fuzes are covered by removable fairings. Ordinarily two fuzes are employed, one at each end of the bomb.

While this system is very effective and positive in its action, it has certain serious disadvantages, particularly on present day high speed aircraft. The wires 18 of the Hale patent are left flapping violently after the bomb is dropped. While a solenoid means is provided to release these wires after they have served their purpose, even a few seconds delay sometimes results in serious damage to the skin of the airplane. The removable fairings are also attached by similar wires so that they will be pulled from the bomb as it is released. Thus there are four wires required for each bomb.

Our invention eliminates the need for the arming wires, the anemometer blades, and the removable fairings. No loose wires remain to damage the plane after the bomb has been released.

Briefly, we restore the arming spring 17 of the Hale patent, provide a safety disk to hold the safety pin in place, and provide an electrically activaetd pyrotechnic delay means to destroy the disk and arm the fuze after the bomb has been dropped.

2,984,185 Patented May 16, 196 1 Referring to the drawing, Figure 1 shows the tire bomb 1 having suspending shackles 2', by which it is suspended by bomb rack 3 from wing 5 of the airplane. At each end of the bomb is a fuze 7 which is shown in the remaining figures.

The fuze' comprises a body member 9 and a head 11 which together form an elongated hollow body member defining a cavity 13 which has conical end walls 15, 17.

Within the cavity is a firing assembly which includes a primer holder 19 and a striker 21. Primer holder 19 carries a primer 23 and engages end wall 17. Striker 21 carries a firing pin 25, and engages conical wall 15. Holder 19 and striker 21 are in telescopic slidable engagement with each other. 7

Firing pin spring 26 is located between primer holder 19 and striker 17 and tends to move them apart. A transverse bore 27 in striker 21 carries locking balls 29 which in their outer position, shown in the drawing, engage a shoulder 31 on holder 19 and prevent relative longitu dinal movement of the holder and striker. They are held in that outer position by arming pin 33.

When arming pin 33 is removed balls 29 are free to move inward to an inner position in which they do not engage holder 19.

Arming pin 33 includes a projecting end portion 35 having a collar 37. An arming spring 39 engages collar 37 and head 11, thus tending to withdraw arming pin 33 from striker 21.

The fuze described so far is essentially the same as that of Hale'Patent 2,420,662, referred to earlier in this specification. Our novel retaining means will now be described.

A yoke 41 is mounted on head 11. As shown in Figures 2, 3 and 4 this yoke is essentially in the form of a hollow cylinder with two segments partially cut away leaving an internally threaded collar 43 at the bottom. At its top, yoke 41 is provided with an internally threaded socket 45 having an annular seat 47 at its bottom.

A threaded cap 49 screws into socket 45. This cap holds a safety disk 51, which fits tightly in an annular recess at the lower end of cap 49, a powder train 53, and an electric squib 55, which is provided with lead wires 57. A safety wire 59, provided with clip 61 passes through projecting end 35 of arming pin 33 and engages yoke 41.

Returning again to Figure 1, bomb 1 is provided with connecting wires 63 to which lead wires 57 are joined. Connecting wires 63 extend from the ends of the bomb to the midpoint, thence out through the bomb casing leads 65 to bomb 3. The leads 65 are joined at this point by a separable connection, e.g. an ordinary plug and socket (not shown) to an electric circuit to the airplane.

Returning again to the cap 49 and its contents, the safety disk 51 is formed of a material which is rigid but easily destructible by heat. A combustible plastic, e.g., cellulose nitrate, is preferred. Powder train 53 is so formed as to give any desired delay between its ignition by electric squib 55' and its destruction of safety disk 51.

The operation of the device is as follows. When the bomb 1 is assembled, filled, and secured to bomb rack 3, the cap 49 is screwed into socket 45 and safety wire 59 is removed. Leads 57 are connected to connecting wires 63 and ends 65 plugged into the proper connection on bomb rack 3. The airplane is provided with a switch which ignites electric squib 55 as, or just before, the bomb is released from bomb rack 3. After the interval of time delay built into powder train 53, the latter destroys safety disk 51. Arming spring 39 then pushes arming pin 33 out of striker 21, releasing locking balls 29. Primer holder 19 and striker 21 are then free to move toward each other against the force of the firing pin spring 26.

Upon impact, firing pin 25 is driven into primer 23, either by inertia or by the camming action of surfaces 15 and 17,'firing pr imer 23 and the usual succession of charges (not shown) all as described in Hale Patent 2,420,662. We claim:

In a bomb fuze comprising an elongated hollow casing defining a cavity having conical end surfaces, a primer holder mounted within said cavity and engaging one of said conical end surfaces, a striker mounted in said cavity in slideable, telescoping relationship with said primer holder and engaging the other of said conical end surfaces, a primer and firing pin mounted in alignment with each other on said primer holder and striker, respectively, locking means between said striker and said holder moveable between an outer position in which they hold said holder and striker against relative longitudinal sliding movement and an inner position in which they allow such movement, an arming pin extending longitudinally of said holder, striker, and casing and having an outer end outside said casing, said arming pin engaging said locking means and holding them in their outer position, and an arming spring engaging said arming pin and tending to withdraw said arming pin out of engagement with said locking means; the combination therewith of a safety disk engaging the end of said arming pin which is outside said casing, retaining means holding said safety disk in position, whereby said arming pin is held in contact with said arming means, said safety disk being destructible by heat, a charge of heat producing composition in contact with said safety disk, and an electric squib in communication with said charge.

References Cited in the file of this patent UNITED STATES PATENTS 1,537,208 Wiley May 12, 1925 2,420,662 Hale May 20, 1947 2,838,999 Corsi June 17, 1958 2,853,010 Bianchi et a1. Sept. 23, 19 58 FOREIGN PATENTS 724,208 France Ian. 25, 1932 

